Setting permissions individually for each user of a database can be a time-consuming and error-prone process. For most databases, permission management based on groups, rather than on individual user IDs, is a much more efficient approach.
You can assign permissions to a group in exactly the same way as to an individual user. You can then assign membership in appropriate groups to each new user of the database, and they gain a set of permissions by virtue of their group membership.
For example, you may create groups for different departments in a company database (sales, marketing, and so on) and assign these groups permissions. Each salesperson is made a member of the sales group, and automatically gains access to the appropriate areas of the database.
Any user ID can be a member of several groups, and inherits all permissions from each of the groups.